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PubMed2006

High exposure to Tunga penetrans (Linnaeus, 1758) correlates with intensity of infestation.

Tungiasis is a parasitic skin disease widespread in resource-poor urban and rural communities in Brazil. Inhabitants of an urban slum in Northeast Brazil were examined for the presence of tungiasis lesions and followed-up twice a week for a period of three weeks. Each time the number, stages, and topographic localization of lesions were recorded on a documentation sheet. The infestation rate (number of newly embedded sand fleas per individual and day) remained stable during the observation period. The infestation rate was significantly related to the intensity of infestation (total number of lesions present) (rho = 0.70, p < 0.0001) and the proportion of viable lesions (rho = 0.28, p < 0.0001). The results indicate that in an endemic area the infestation intensity and the proportion of viable lesions can be used as a proxy to assess the exposure of individuals at risk for tungiasis. Persistently high infestation rates during the transmission season favour the use of prevention measures against invading sand fleas (such as a repellent) rather than a drug to kill already embedded parasites.

Adolescent↗
PubMed2006

Improved dry-fleshed sweetpotato genotypes resistant to insect pests.

Thirty-five mostly dry-fleshed sweetpotato, Ipomoea batatas (L.) Lam. (Convolvulaceae), genotypes from the USDA-ARS/Clemson University sweetpotato breeding program were evaluated in nine field experiments at the U.S. Vegetable Laboratory, Charleston, SC, from 1998 to 2004. There were highly significant entry effects for percentage of uninjured roots; wireworm, Diabrotica, and Systena (WDS) index; percentage of roots damaged by sweetpotato weevil, Cylas formicarius elegantulus (Summers); percentage of roots damaged by sweetpotato flea beetle, Chaetocnema confinis Crotch); and percentage of roots damaged by white grub larvae (primarily Plectris aliena Chapin). The susceptible control, 'SC1149-19', had a significantly lower percentage of uninjured roots, a significantly higher WDS rating, and higher percentage infestations of flea beetle, grubs, and sweetpotato weevils than all other sweetpotato entries in this study. Twenty-seven genotypes had significantly less insect damage than 'Beauregard', the leading commercial orange-fleshed cultivar in the United States. In addition, 11 genotypes had significantly less insect injury than 'Picadito', a commercial boniato-type sweetpotato grown extensively in southern Florida. Overall, no genotypes were more resistant to soil insect pests than the resistant checks 'Sumor' and 'Regal'. Many of the advanced dry-flesh sweetpotato genotypes had high levels of resistance to soil insect pests, and they represent a useful source of advanced germplasm for use in sweetpotato breeding programs.

Animals↗
PubMed2000

Ectoparasites and gastrointestinal helminths of southern flying squirrels in southeast Georgia.

Southern flying squirrels (Glaucomys volans) from southeastern Georgia were examined for ectoparasites and gastrointestinal helminths. Ten species of ectoparasites were recovered, including 3 species of sucking lice (Hoplopleura trispinosa, Microphthirus uncinatus, and Neohaematopinus sciuropteri), 1 species of flea (Orchopeas howardi), 2 species of ticks (Amblyomma maculatum and Ixodes scapularis), 3 species of mesostigmatid mites (Androlaelaps casalis, A. fahrenholzi, and Haemogamasus ambulans), and 1 species of chigger (Leptotrombidium peromysci). Only the sucking lice and fleas were common on this host. M. uncinatus is reported for the first time from eastern North America. The 2 most commonly collected ectoparasites, N. sciuropteri (prevalence = 63%) and O. howardi (prevalence = 47%), have previously been shown to be vectors of the rickettsial zoonotic agent that causes sporadic epidemic typhus. Also, 3 nematodes (Citellinema bifurcatum, Strongyloides robusius, and Syphacia thompsoni), 1 unidentified cestode, and 1 acanthocephalan (Moniliformis clarki) were found in flying squirrel gastrointestinal tracts. With the exception of S. thompsoni, which was common and relatively abundant in the cecum (prevalence = 94%, intensity = 51+/-12), both the prevalence and intensity of helminth parasites were low. The nematode S. thompsoni and the acanthocephalan M. clarki are new state records for tree squirrels in Georgia.

Animals↗
PubMed2006

Sexual dimorphism in Bosmina: the role of morphology, drag, and swimming.

Some Bosmina water flea species develop morphological antipredatory defenses, such as long antennules and a high carapace, but in Bosmina (Eubosmina) coregoni gibbera these traits are larger and more variable in females than in males. Here we propose that this sexual dimorphism derives from differential costs of hydrodynamic drag and selection for mobility in males. We tested this hypothesis by estimating drag of several Bosmina morphologies by using scale models sinking in glycerin of different concentrations and viscosities. Body forms included males, sexual and asexual females of B. c. gibbera, and males and asexual females of Bosmina (Eubosmina) longispina, a taxon with less variable body shape. For a given body length or body volume, male models had lower drag than models of sexual and asexual females, suggesting that males can swim 14-28% faster with the same energy consumption. Consistent with this conclusion, video recordings showed that males of B. c. gibbera advanced 55-73% farther than females in each swimming stroke. We conclude that hydrodynamic drag may have significant implications for swimming and evolution of sexual dimorphism in water fleas, and we suggest that males lack the defensive structures of females of B. c. gibbera (e.g., high carapaces) because competition over mates favors low drag.

Animals↗
PubMed2005

Effects of hydrogen sulfide to Vibrio fischeri, Scenedesmus vacuolatus, and Daphnia magna.

The effects of hydrogen sulfide (H2S) were tested in three ecotoxicological tests in order to evaluate its confounding potential in assessment of pore water and groundwater toxicity. The luminescent bacteria Vibrio fischeri, the water flea Daphnia magna, and the microalgae Scenedesmus vacuolatus often are part of a biotest battery. A new technique for the synthesis of hydrogen sulfide solutions of defined concentrations using an electrochemical generator instead of sodium sulfide solutions was used. Because hydrogen sulfide is volatile, the loss rate of H2S was studied over time to enable estimation of the mean test concentrations over the whole test duration. Loss rates were calculated to be 13 +/- 6% after 30 min, and 39 +/- 11% and 43 +/- 16% after a 24- and 48-h exposure time, respectively. Sensitivities of the test organisms in terms of median effective concentration (EC50), corrected for the above loss rates, varied from 0.28 to 0.0036 and 0.055 mM for the luminescent bacteria, the crustacea, and the algae, respectively. A species-sensitivity distribution using EC and mean lethal concentration literature data for marine and freshwater crustaceans and phytoplankton showed a medium sensitivity of the water flea D. magna, though the bacteria V. fischeri and the algae S. vacuolatus were among the least-sensitive group of organisms. This demonstrates that only the algae and the bacteria are easy to use in the assessment of toxicity of matrices with H2S concentrations above 0.06 mM.

Air Pollutants↗
PubMed1984

Occurrence and impact of zoonoses in pet dogs and cats at US Air Force bases.

A descriptive epidemiologic study was conducted to quantitate the occurrence of zoonoses in pet animals (almost exclusively dogs and cats) at 30 Air Force bases in nine regions of the United States during 1980 and 1981. Reviews of reported cases of pet-associated zoonoses in humans at these bases were included. Occurrence of a zoonotic disease in dogs and cats was expressed as a ratio of reported cases per 100 rabies vaccinations (cs/Crv). Overall, the four zoonoses reported most frequently from these pets were hookworms, roundworms, tapeworms, and fleas. Annual ratios revealed geographic variations: for example, hookworms in dogs and cats in the southeast ranged from 12.3 to 9.4 cs/Crv; in the northern Great Plains, hookworms ranged from 0.9 to 0.4 cs/Crv. Dermatomycoses in the southeast ranged from 1.3 to 1.1 cs/Crv, and in Alaska from 0.3 to 0.2 cs/Crv. Quarterly zoonoses occurrence revealed seasonal variations in several regions. Reports of zoonoses in people from these bases indicated that five less frequent zoonoses in dogs and cats (Microsporum canis dermatomycosis, fleas, Sarcoptes scabiei var canis, Gram-positive bacterial infections, and rabies) presented greater acute threats to humans than did the four most frequent zoonoses reported from their pets.

Adult↗
PubMed2005

Bartonella quintana and Rickettsia felis in Gabon.

We detected Rickettsia felis DNA in Ctenocephalides felis and Bartonella quintana DNA in 3 Pulex irritans fleas taken from a pet Cercopithecus cephus monkey in Gabon, sub-Saharan Africa. This is the first report of B. quintana in the human flea.

Animals↗
PubMed1994

Cat-transmitted fatal pneumonic plague in a person who traveled from Colorado to Arizona.

Plague, primarily a disease of rodents and their infected fleas, is fatal in 50% of infected humans if untreated. In the United States, human cases have been concentrated in the southwest. The most common modes of plague transmission are through flea bites or through contact with infected blood or tissues; however, primary pneumonic plague acquired from cats has become increasingly recognized. We report on the case investigation of a patient, presumably exposed to a plague-infected cat in Colorado, who presented with gastrointestinal symptoms, and subsequently died of primary pneumonic plague. Public health officials should be vigilant for plague activity in rodent populations, veterinarians should suspect feline plague in ill or deceased cats, and physicians should have a high index of suspicion for plague in any person who has traveled to plague enzootic areas.

Adult↗
PubMed2002

Ectopic localization of tungiasis.

Tungiasis is caused by the penetration of the female sand flea Tunga penetrans into the epidermis. It is generally assumed that lesions are confined to the feet. To determine to what degree tungiasis occurs at other topographic sites, 1,184 inhabitants of a poor neighborhood in northeastern Brazil were examined; 33.6% were found to have tungiasis (95% confidence interval = 30.9-36.4%). Six percent presented lesions at locations other than the feet, with the hands being the most common ectopic site (5.5%). Other sites were the elbows, thighs, and gluteal region. Ectopic tungiasis was significantly associated with the total number of lesions (P < 0.001) and an age less than 15 years old (P = 0.02). In 86 patients actively recruited with lesions on their feet, ectopic localizations were observed in 25.6%. Since untreated sand flea lesions are prone to become superinfected, clinicians should be aware of not missing any ectopic localization of tungiasis.

Adult↗
PubMed2002

Typical histologic features of Tunga penetrans in skin biopsies.

CONTEXT: Tunga penetrans is a flea that burrows into human skin, causing the disease tungiasis. Although the parasite is not endemic in the United States, patients may present with this disease upon returning from tropical locales. Histologic sections contain a variety of flea parts that may present a diagnostic dilemma for pathologists unfamiliar with this disease. OBJECTIVE: To determine the typical histologic features of T penetrans in biopsies from patients with tungiasis. METHODS: We reviewed biopsy specimens from 7 patients with tungiasis and sought 8 distinct structures: the exoskeleton, hypodermal layer, respiratory tract (tracheae), digestive tract, striated muscle, head, posterior end, and developing eggs. RESULTS: The exoskeleton, hypodermal layer, tracheae, digestive tract, and developing eggs were present in all biopsy specimens reviewed. Striated muscle, the posterior end, and head, however, were present in 57%, 43%, and 0% of the biopsies, respectively. In addition, we noted a unique, pale-staining layer in the exoskeleton at the posterior end of the organism that, to the best of our knowledge, has not previously been described and that may be of diagnostic value. CONCLUSIONS: Despite the absence of 3 key morphologic features in many (posterior end and striated muscle) or all (head) of our biopsies, the exoskeleton with a hypodermal layer, tracheae, and developing eggs were uniformly present, and together these features are sufficient for a diagnosis of tungiasis.

Adult↗
PubMed1980

Modes of ectoparasite reinfestations of deer mice (peromyscus maniculatus).

Modes of ectoparasite reinfestations were studied on ectoparasite-free deer mice (Peromyscus maniculatus) returned to their natural habitat on the Tule Lake National Wildlife Refuge, Siskiyou County, California, during the summer of 1977. The age of the host made no significant difference in the mode of reinfestation of lice, fleas, or mites. Flea reinfestation rates were related to the sex of the host, requiring 4 and 2 days, respectively, to reach control levels on male and female hosts. Mite populations reached the control level within 1 day, regardless of the sex of the host. No statistically significant louse reinfestations were noted within 8 days after the hosts were released. The percent of the host population reinfested with each ectoparsite followed the same patterns of reinfestation as the numbers of each parasite per host. It is suggested that the mode of ectoparasite reinfestations is a function of the behavior of the host relative to the lifestyles of the ectoparasite species.

Age Factors↗
PubMed1988

A plague epizootic in the white-tailed prairie dogs (Cynomys leucurus) of Meeteetse, Wyoming.

Surveillance for sylvatic plague (Yersinia pestis) was conducted near Meeteetse, Wyoming (USA) from 24 May to 14 June 1985. Ten species of fleas were collected from white-tailed prairie dogs (Cynomys leucurus), and from their burrows and associated rodents. Five of these flea species and two adult prairie dogs were positive for plague. The progression of this plague epizootic appeared to be slower and the intensity was less than in previous epizootics in other prairie dog colonies. The plague epizootic occurred within the only known colony of black-footed ferrets (Mustela nigripes) and was a potential threat to the food source of this endangered species.

Animals↗
PubMed1997

Entomological and rodent surveillance in plague-suspected areas during September 1994 and thereafter.

Studies carried out in the states of Maharashtra, Gujarat, Uttar Pradesh and Union Territory of Delhi after the bubonic plague outbreak during 1994 revealed the presence of seven species of rodents, viz. Rattus rattus, R. norvegicus, Mus. musculus, Tatera indica, Suncus murinus, Bandicoota bengalensis and B. indica. The flea species encountered were Xenopsylla cheopis and X. astia. The X. cheopis and X. astia index recorded in different areas of Beed district of Maharashtra; Surat, Vadodra and Baruch districts in Gujarat and Varanasi district in Uttar Pradesh and their implications have been discussed. Insecticide suspectibility tests carried out against DDT, dieldrin, malathion and deltamethrin with X. cheopis collected from Maharashtra, Delhi and Varanasi revealed that this vector species is resistant to DDT and dieldrin but susceptible to malathion and deltamethrin. The prevalence and distribution of rodents species, high cheopis index and prevalence of Tatera indica just at the door steps of houses in village Mamla of Beed district provides highly congenital conditions for the intermingling of wild and domestic rodents and transfer of flea population from wild to domestic rodents and vice-versa. These conditions were found to be highly supportive for bubonic plague transmission in the district. The presence of Yersinia pestis antibodies in Rattus rattus collected from Beed, Surat and Varanasi areas are also indicative of bubonic plague in Beed and Varanasi and pneumonic plague in Surat during 1994.

Animals↗
PubMed1999

Effects of feeding on the circadian rhythm of Ceratophyllus s. sciurorum (Siphonaptera: Ceratophyllidae).

Circadian rhythm in newly emerged blood-fed individuals of the flea Ceratophyllus s. sciurorum was studied in a constant environment, using an insect activity monitor. The results of trials run continuously over seven days confirmed the finding that C. s. sciurorum has a self-sustaining clock. Statistical tests confirm that feeding weakens the rhythm but does not eliminate it. There was a significant difference in the mean activity between the fed and unfed fleas, reflecting the difference in the number of hours over which this activity took place. A possible commercial application for the monitor and also for the method of analysis is discussed.

Animals↗
PubMed2000

Winter ectoparasites of mammals in the northeastern piedmont area of Georgia.

Twenty-three species of ectoparasites were recovered from 10 species of mammals (89 individuals) in Mistletoe State Park, Columbia County, Georgia, during three winter months of 1998. The collection consisted of 9 species of fleas, 6 mites, 4 sucking lice, 3 ticks, and 1 mammal-associated beetle. Some rarely-collected arthropods were recorded including the ctenophthalmid fleas, Doratopsylla blarinae C. Fox and Epitedia cavernicola Traub, the laelapid mite, Echinonyssus blarinae (Herrin) (first records from Georgia for these three ectoparasites), and the leptinid beetle, Leptinus orientamericanus Peck (second record for Georgia). Varying degrees of host-specificity were exhibited by the 23 species of ectoparasites. Because relatively few mammal ectoparasite surveys are completed during the winter months, some seemingly rare species may, in reality, be more common at this time of year.

Animals↗
PubMed1999

[The plague reviewed by way of molecular biology].

The aetiology of plague was first discovered during the third pandemic of the disease occurring in Hong Kong in 1894. After Alexandre Yersin had identified the causal agent (Y. Pestis), Paul-Louis Simond proved the flea's role as vector. These discoveries were of prime importance for the subsequent development of efficient means for fighting plague as well as for preventive and curative treatments and vaccines. Vaccination brought about a sharp decrease in plague mortality and morbidity. However, the disease has never been eradicated. It is still prevalent in various Asian, African and American countries and is among the re-emerging diseases at the present time. The genetic basis of transmission mechanisms and pathogenicity of the bacillus are only beginning to be understood. We now know that the attenuation of the EV76 strain used by Girard and Robic as an anti-plague vaccine in Madagascar is due to the spontaneous excision of a large chromosomal DNA fragment of 102 kb, a part of which contains a group of genes implicated in the pathogenicity and appropriately called high pathogenicity island. These mechanisms of flea bacillus transmission are also beginning to be known. Two bacterial loci participating in the blocking of the ectoparasite's proventriculus have been identified. One is situated next to the high pathogenicity island on the unstable 102 kb chromosomal fragment, the other--on the large 95 kb plasmid specific to Y. pestis. The molecular basis of the bacillus' acquisition of multi-resistance to antibiotics have likewise recently been characterised. However, although Y. pestis is one of the most pathogenic micro-organisms of the bacterial world, the mechanisms responsible for this high level of pathogenecity have still not been identified. This is well worth noting, since a certain number of genes acting as pathogenicity factors in other species are present but altered in Y. pestis. Plague still withholds many secrets.

Animals↗
PubMed1999

[The black rat (Rattus rattus) and the plague in ancient and medieval western Europe].

The first time plague affected Western Europe was in the early Middle Ages: rom 541 to 767, there were no fewer than 15 outbreaks in southern parts of the continent. Plague then disappeared from Europe for some seven centuries but came back with a vengeance in 1347, this time by way of the Mediterranean, and ravaged the entire continent for five years, resulting in a serious demographic depression. From then on until 1722 (and 1771 in Moscow), the disease remained endemic to Europe, periodically undermining its economy. These epidemics were major determinants of medieval history, but their study has not been completed to this day. It was not until the 1970s that archeo-zoologists finally discovered that the black rat had indeed been present in Europe since Roman times. Further extensive research revealed that the rat population had gradually grown from a fairly restricted one in the early Middle Ages to a significant one in the 11th and 13th centuries. The rodents spread along the major highways explaining the very different geographical impact of the various plague epidemics of the early and late medieval periods. However, the mystery of the exact mechanisms by which plague spread has still not been entirely elucidated, since the Asian rat flea, Xenopsylla cheopis, whose role as vector was demonstrated by P. L. Simond, could not have survived in the temperate European climate. Thus, the question of the European vector is still left hanging: was it a human or a rat flea? Was the rat a propagator or simply an initiator? This article considers these unresolved questions by re-examining P. L. Simond's very precise observations.

Animals↗